Mechanism for converting rotary motion into reciprocating motion



Oct ,1939. F; v BOXALL 2178.247

MECHANISM FOR CONVERTING ROTARY MOTION INTO RECIPROCA'IING MOTION FiledOct. 12, 1958 2 Sheets-Sheet l F. c. BOXALL 2,178,247

MECHANISM FORv CONVERTING ROTARY MOTION INTO RECIPROCAT ING MOTION FiledOct. 12, 1938 O ll jwemvn' Wr/ZWM 5 KMWM v H; I

2 Sheets-Sheet 2 I Patented st. 31, 1939 MECHANISM FOR CONVERTING ROTARYMOTION INTO RECIPROCATING MOTION Application October 12, 1938, SerialNo. 234,678 In Great Britain October 26, 1937 UN-l'i' tsTAi' 6 Claims.

This invention is for improvements in mechanism for converting rotarymotion into reciprocating motion, such as may be used for driving theplunger of a reciprocating pump from a ro- Figure 4 is a view similar toFigure 2 but showing the parts in outside elevation and in a differentrelative position; and

Figure 5 is a section on the line 55 of Figure 4.

tating shaft; it may also be used, in suitable cir- As shown in thedrawings, a plunger It of a 5 cumstances, for the conversion ofreciprocating high-speed reciprocating pump is slidable in a motion intorotary. cylinder I! supported by a frame-member l2. According to theinvention, mechanism for con- It is required to reciprocate the plungerl0 by verting rotary motion into reciprocating motion rotating a shaftl3 which is borne in a bearing comprises, in combination, a reciprocableele- M Ca ed by a frame-member 5- e f ment, an eccentric-devicerotatable about an axis members 82 and i5 and also the frame-memberparallel with the direction of reciprocation of i6 described below aresupported in a housing ll said reciprocable element, a rod so connectedto of any convenient construction. said eccentric-device that one pointin its length The end of the shaft 13 is formed with an s dr ven in acircle and so guided as to pass eccentric recess containing a cup I8which re- 15 through a fixed point which is offset both latceives theball-shaped end IQ of a cylindrical rod erally from the axis of rotationof the eccentric- 26, the other end of which is forked at 2| to endeviceand longitudinally from the point of congage a tu u ar d -Din 22 uponwhich the nection from the rod to the eccentric-device, and tongue-end23 of a bent coupling rod 2 3 is piva coupling between said reciprocableelement'and oted. The other end of the rod is formed with a anotherpoint on the rod. ball-end 25 which engages a cup 26 in the end ofAccording to another feature of the present the plunger l0. invention,the mechanism comprises, in combi- The cylindrical rod 20 is slidable ina diametral nation, a reciprocable element, an eccentric-debore in aball 21 which is supported for tilting vice, a rod so connected to saideccentric-device movements in part-spherical recesses in plates 25 thatone point in its length is driven in a circle, 28 secured to aframe-member IS. a ball rotatably mounted in a part-spherical As can beseen from Figure 4, the axis of rotahousing and having a bore engagingthe rod, tion 29 of the shaft i3 and the axis 36 of the whereby the rodcan slide in the bore and tilt plun er I l re p r n p ed p r h about thecentre of the ball, and a coupling becentre 3| of the ball 2! lies onthe side of the 30 tween the said reciprocable element and another axis30 remote from the axis 29. However, the point on the rod. axes 29 and30 and the centre 3i lie all in the According to another feature of theinvention, same vertical plane as may be seen from Figthe parts are soarranged, for a purpose explained ure 1. hereinafter, that the point ofconnection of the The knuckle-joint constituted by the forked 5 rod tothe eccentric-device, the point of the conend 2| of the rod 20, thegudgeon-pin 22, and nection of the rod to the coupling, and the pointthe tongue-end 23 of the curved rod 24, is held of connection of thecoupling to the reciprocable together by a locking Wire 32 which passesalong element can never lie on the same straight line. the bore of thegudgeon-pin and has its ends This condition may be achieved by ensuringthat, pressed into suitable holes in a flange 33 forme where the axis ofthe reciprocable element is on the bent rod 24. parallel with the axisof the shaft but displaced When the shaft i3 is rotated the ball H)detherefrom, the centre of the ball does not lie bescribes a circleabout the axis 29. Consequently tween the said axes, although it may lieon the the axis of the rod 20 generates the surface of a same plane.distorted cone, the necessary tilting movement Aspecific embodiment ofthe invention will now being permitted by tilting of the ball 21 in itsbe described by way of example with reference to housing 28. By reasonof the fact that the the accompanying diagrammatic drawings in centre 3!of the ball 27 is offset from the axis of which: rotation 29 of theshaft l3, the remote end 2! Figure l is a plan View of mechanismaccordof the rod 20 does not describe a circle in a plane ing to theinvention; at right-angles to the axis 29 but describes a non- Figure 2is an elevation being a section on the circular closed figure lying atan oblique angle line 2-2 of Figure 1; to that axis. Hence, the forkedend 2| has a Figure 3 is a section on the line 3-3 of Figcomponent ofmovement parallel with the plungure 2; er-axis 30, and the. coupling rod24 transmits this component to the plunger which is therebyreciprocated. Figures 2 and 3 show the parts in one dead-centre positionand Figures 4 and 5 show the parts in the position they assume when theshaft [3 has been rotated through 130 from the position shown in Figure2.

It will be seen that the rod 2% and the rod 28 experience considerablerelative angular movement so that the knuckle-joint illustrated is moresuitable than a ball joint at this point. However, where a knuckle-jointis used, it is necessary so to design the mechanism that the centre ofthe ball the centre of the gudgeonpin 22, and the centre of the ball 8%shall never lie in the same straight line in space otherwise theknuckle-joint will lock in certain positions of the parts. There aremany ways of ensuring that the three points above mentioned shall notlie in a straight line, but one way is to arrange that the centre of theball 2'! does not lie between the axes 29 and 38; this arrangement isclearly shown in Figure 4.

It will be seen that the coupling rod 24, in elevation, oscillates withrespect to the axis 3!] of the plunger. In order to bring the meanposition of the left-hand end of the rod 24 near to the axis 35, andthereby simplify the construction of the ball-housing 26, the rod 24 iscurved as shown so that its left-hand end is approximately in line withthe plunger.

The lengths of the rods 25 and 24 and the distance between the ballcentre 3i and the axes 29 and 3G may be so designed as to give anydesired stroke to the plunger iii.

The advantages of the invention are that it is possible to arrange theplunger and shaft substantially in line, whereby a compact assembly ispossible, and that the mechanism is capable of being driven at highspeeds for long periods without undue wear.

I claim:

1. Mechanism for converting rotary motion into reciprocating motioncomprising, in combination, a reciprocable element, an eccentric-devicerotatable about an axis parallel with the direction of reciprocation ofsaid reciprocable element, a rod connected to said eccentric-device atone point in its length so that the rod at the point of connection isdriven in a circle, said rod being so guided as to pass through a fixedpoint which is offset both laterally from the axis of rotation of theeccentric-device and longitudinally from the point of connection of therod to the eccentric-device, and a coupling between said reciprocableelement and another point on the rod.

2. Mechanism for converting rotary motion into reciprocating motioncomprising, in combination, a reciprocable element, an eccentric-devicerotatable about an axis parallel or approximately parallel with thedirection of reciprocation of said reciprocable element, a rod connectedto said eccentric-device at one point so that the point in its length isdriven in a circle, a ball rotatably mounted in a part-spherical housingand having a bore engaging the rod whereby the rod can slide in the boreand tilt about the centre of the ball, which centre is offset laterallyfrom the axis of rotation of said eccentric device and a couplingbetween said reciprocable element and another point on the rod.

3. Mechanism for converting rotary motion into reciprocating motioncomprising, in combination, a reciprocable element, an eccentric-devicerotatable about an axis substantially parallel with the direction ofreciprocation of said reciprocable element, a rod connected to saideccentric-device so that the point of connection is driven in a circle,a coupling between said reciprocable element and another point on therod, and a ball rotatably mounted in a part-spherical housing and havinga bore engaging the rod between its points of connection to theeccentricdevice on the one hand and the coupling on the other hand andhaving its center displaced laterally from the axis of rotation of saideccentric device whereby the rod can slide in the bore and tilt aboutthe centre of the ball.

l. Mechanism as claimed in claim 1, wherein the parts are so aranged,for the purpose described, that the point of connection of the rod tothe eccentric-device, the point of connection of the rod to thecoupling, and the point of connection of the coupling to thereciprocable element can never lie on the same straight line.

5. Mechanism for converting rotary motion into reciprocating motioncomprising, a reciprocable element, an eccentric-device rotatable aboutan axis parallel with the direction of reciprocation of saidreciprocable element but displaced therefrom, a rod connected to saideccentric-device at one point in its length so that the rod at the pointof connection is driven in a circle, a ball having its centre displacedlaterally from the axis of rotation of the eccentric device lying in theplane containing the axes of the eccentric-device and reciprocableelement but not lying between them, and a part-spherical housing inwhich the ball is rotatably mounted whereby the rod can slide in theball and tilt about the centre of the ball.

6. Mechanism as claimed in claim 2, wherein the said coupling is acurved rod for the purpose described.

FREDERICK CHARLES BOXALL.

